So I just got my tranny rebuilt.. I had to drive 650 miles after i got it rebuilt, the first 340 miles car drove perfectly fine and sounded great but once it hit like 400 miles i started hearing this whirring sound . The car drives great and gears slip in pretty good but I just dont know what that sound is? I have never heard it until recently and I know its the tranny i can literally hear the gears turning in the tranny and when I slow down I can hear them like if they were next to my ear? How can I stop this noise? Could it be that they rebuilt the tranny wrong or do I need defferent oil we used 80/90 tranny oil!